1. Field of the Invention
The present invention relates to a display device, particularly, a display device using an organic EL element.
2. Description of the Related Art
FIG. 29 shows each pixel circuit of an organic EL (Electro Luminescence) display of the related art. As shown in FIG. 29, the respective pixel circuits have an organic EL element 201, a driving TFT (Thin Film-Transistor) 202, a capacitor 203, a TFT switch 204, and a TFT switch 205.
Specifically, as shown in FIG. 29, an anode of the organic EL element 201 is connected to a power source Voled via a driving TFT (Thin Film-Transistor) 202, and a cathode thereof is grounded. Furthermore, a signal depending on a display voltage is input to a gate of the driving TFT 202 via the TFT switch 204, and a predetermined voltage is input to the source via the TFT switch 205. The capacitor 203 is connected between the gate and the source of the driving TFT 202.
Next, operations of the respective pixel circuits will be described. The TFT switches 204 and 205 are turned on, and an electric potential difference between the signal voltage and the predetermined voltage is held at both ends of the capacitor 203. After that, by turning the TFT switches 204 and 205 off, the electric potential difference held at both ends of the capacitor 203 is output between the gate and the source of the driving TFT 202. Moreover, the driving TFT 202 causes the organic EL element 201 to emit light by the driving electric current depending on the signal voltage. The pixel circuits of the related art as described above are disclosed in Japanese Patent No. 4052865 or Japanese Patent No. 3877049.